Thinking about a ring & pinion swap

[WBissell]

Hello everyone. I was thinking about swapping my stock 3. 54's to 3. 73 or even 4. 10's. The reason is my concern over towing our new 5th wheel. My thinking is that lowering the gear ratio would make life easier on the drivetrain (namely the transmission which is my concern) and allow for faster hill pulls.

The new rig will weigh around 10K lbs loaded. While I know the engine is more than a match for this weight, I believe the transmission is the weak link in the drivetrain. My other concern is RPM's driving 65 on the freeway. Would it make for a noisy ride?

We pick up the new rig on Friday and I will tow it home (from Salem, OR. to Seabeck, WA. ) with the current gears and see how she handles it. I have a transmission temp guage so I will monitor it.

Just looking for your opinions.

Thanks

 

[Flexiheep]

Well, good luck with the new trailer, just got mine 6 weeks ago and already did a 4500 mile trip. While it isn't a tall fiver my TT is still 11' and some change and 9K dry, so around your specs. I did the first 2K with the stock transmission with 250K on it, it was interesting to say the least! I couldn't run overdrive even on the flat, at 60 mph I would watch it easily pass 240 degrees. Drop into 3rd and pulled at 190 all day, but 62 mph was top end, pump started to defuel. Pulled 3 major passes (one on 8 going into San Diego, grapevine and Sysque ?) and did them in 2nd gear at 42 mph trying to stall the TC as much as possible, still was running 260 plus and climbing at the top.



In the middle of the trip I met up with my previously ordered ATS transmission and had it installed. Well it is basically a new truck again, right down to the driveline shudder due to the 6" rear blocks. I forgot all about it since the transmission slipped so much even under load it was smooth. I not run the same passes in 3rd gear at 50-55, temps around 200 and I can drive anything from flat to about 3% grade easily in od now.



My recommendation is that I would put the money from a gear change into a good TC for the transmission. I found that I was already plenty high in the rpm range(2K+) while climbing, I don't think lower gears would have helped really, since your not supposed to load overdrive that much.



Yes 3rd gear for 2000 miles at 2400 rpm(62 mph) was a bit wearing, my wife and I were really happy to run in 4th for the trip home (still around 62 mph).



For reference to the condition of my transmission i joked that Dodge put the first CVT transmission in a full sized truck, I couldn't feel a shift, hear an engine load change or anything in my truck. You hit the gas and it held 2K rpm till you let off at the speed you wanted.



transmission temps are on the TC outlet (line to the coolers) and I do not have a superduty cooler (under bed). I do plan to add one though.



ATS transmission has double deep finned pan (8 qts extra) and their TC to help control heat.

 

[dpuckett]

I second the move to get a better convertor/ valve body rather than swap gears. You will still have your empty MPGs, while maintaining your pulling power. Bump the engine up a few ponies, and have fun. Plus, you can go faster and get better MPGs, esp when the power is transferred efficienty. I sold my first CTD because of the stock auto transmission (92 D350 in 99), and it would have been $2grand+ to get it upgraded. And there werent as many options then as there are now.



Flexiheep- you got 3. 54s or 4. 10s? Reason I ask is my mom's (the one mentioned above) will do 73-75 in 3rd, stock or near stock RPMs. Couple trucks with 4. 10s I've had would top out around 60 with stock RPMs in direct.



Daniel

 

[WBissell]

Flexiheep - Can you give more details on the ATS transmission? I know of the company, based in Colorado, I think? Did you replace the entire transmission or just the TC? What kind of $$ did that set you back?

My dad had a '93 CC with auto and 4. 10's. His mileage was still around 19mpg empty. He towed a similar 5'r and didn't have any problems, hence my thinking of the gear swap.

Thanks for your input. Really appreciate it.

 

[Flexiheep]

Details Details Details, everyone always wants the whole story... .



I have 3. 54 gears, and my 62 MPH was with the 10K lb sail attached (TT is over 11' tall). I would believe the mid seventy's empty as I lost a couple hundred rpm under the load of the trailer. I might be able to get it faster even with the trailer but I wasn't in the mood to push it on the way home.



The ATs unit was a "normal" unit in that I didn't order anything special (billet shafts or anything), just their advertised 518. From what I can see all the big name trannys are the same for our trucks for the most part. All have extra clutchs and friction plate, heavy full wrap bands, modded valve bodies, late model OD baskets etc. The unit I was sent actually was in a 47 series case (shop had to pull it back out as some reinforcements interfered with the 205 shifter). I does show how interchangable the Dodge trannys are though. I also got their TC as it was easier than ordering from someone else and if I trusted them with the transmission... . It is again like the others, billet housing and some kinda special VOODOO that they do... .



I was on the wall about buying a transmission and building my own, the cheap control freak in my wanted to save bucks and do it myself, but mainly due to time constraints relating to our TT purchase and trip date I decided to order up a unit and have it shipped to the dealer in Albany OR (on our trip route). I left NM hoping the transmission would hold together till I got there, and it did (kinda impressed that the transmission held together with 250K miles at 4K over "rated" towing weight).



I do plan to work on the cooling system though, the coolant based atf cooler is great at shedding transmission heat but I don't like putting that heat in the radiator as that reduced the heat that the engine can shed. I guess I will have to figure out a good large capacity under bed cooler or two that will keep it cool and free up the radiator for the extra Btus that the engine mades under load.....



Oh yah as to what it set me back... ...

transmission 2100

TC 900

updated flex plate 140

install 600

shipping 300?



So yah it set me back a couple bucks, but hey I didn't have time to do it myself and I shouldn't have to worry about it for a long time. Plus this truck will be around for a while as it turns into a crewcab (mom dad and carseat fill the bench seat)... ...



One thing I did like was the 3 year 100K warranty that they have, longest I saw on the ones I was looking at.



There are much cheaper options if you have time and or a lower mile transmission, but with 250K on mine I didn't feel good about just getting a better converter and most likely toasting the worn out internals. If your transmission is in good shape, get a tighter converter and an under bed cooler and go.



Yes if you look under my truck it has a barney purple transmission, luckily most people don't look under there. :-laf



Since I know someone will ask I was getting 10 mpg with the stock transmission while towing at 60, didn't matter if it was flat or a mountain pass... I get just a little better now, maybe 10. 5 or so same conditions. Any mileage increase while clinbing is negated by the 10 mph extra (3rd instead of 2nd) I run up the hills now.



Any more questions?

 

[DBF]

Hello everyone. I was thinking about swapping my stock 3. 54's to 3. 73 or even 4. 10's. The reason is my concern over towing our new 5th wheel. My thinking is that lowering the gear ratio would make life easier on the drivetrain (namely the transmission which is my concern) and allow for faster hill pulls.



Just looking for your opinions.



Thanks

My opinion is that you (1) look at this link:

http://www.dieseltrans.com/dodge/index.htm



and then (2) make an appointment for a transmission inspection/evaluation and installation of a 3200rpm governor spring into your injection pump, run up to BC and do that,



and then (3) take a number and come back a week later to do what Bill Kondolay advised regarding a new torque converter and adjustments to the valve body, taking into account your needs.



It's easy enough to run up to Port Townsend & Whidbey Island, then up to Abbotsford, BC.



The spring will give you a larger range of RPMs (you won't believe the difference). The stiffer torque converter Bill will recommend will just flat astound you.



Testamonial: My DTT stuff (see signature) has lasted six years, 55+kmiles, three Alaska trips, one Newfoundland trip, all towing my 8k 5er. When I finally took it in for inspection, it just barely needed tweaking. Fantastic.



I'll be in western Montana this summer if you want to meet up and shoot the bulls.



Regards, DBF

 

[boatpuller]

I second DBF's recomendation(I would take a different route to get there but his will work). If you would like to check out a truck with a DTT transmission, I'm in Silverdale, right next door to Seabeck.



Caleb

 

[WBissell]

Ok... I'm starting to get the idea that maybe a transmission swap would be a smarter choice. I'd like to hear from the guys and gals who have done a ring & Pinion swap though. Anyone out there?

I may start a new thread for this.

Thank you all for your replys. And I may take you up on checking out your rig, boatpuller. I viewed your pics... nice rig.

 

[Niki]

I second what DBF said about the governor spring, when you have to go into third for the hills it'll give you more RPM.